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Introduction

Any activity that produces or uses radioactive materials generates radioactive waste. Mining, nuclear power generation, and various processes in industry, defense, medicine, and scientific research produce byproducts that include radioactive waste. Radioactive waste can be in gas, liquid or solid form, and its level of radioactivity can vary. The waste can remain radioactive for a few hours or several months or even hundreds of thousands of years. Because it can be so hazardous and can remain radioactive for so long, finding suitable disposal facilities for radioactive waste is difficult. Depending on the type of waste disposed, the disposal facility may need to contain radiation for a very long time. Proper disposal is essential to ensure protection of the health and safety of the public and quality of the environment including air, soil, and water supplies.

Radioactive waste disposal practices have changed substantially over the last twenty years. Evolving environmental protection considerations have provided the impetus to improve disposal technologies, and, in some cases, clean up facilities that are no longer in use. Designs for new disposal facilities and disposal methods must meet environmental protection and pollution prevention standards that are more strict than were foreseen at the beginning of the atomic age.

Disposal of radioactive waste is a complex issue, not only because of the nature of the waste, but also because of the complicated regulatory structure for dealing with radioactive waste. There are a variety of stakeholders affected, and there are a number of regulatory entities involved. Federal government agencies involved in radioactive waste management include: the Environmental Protection Agency (EPA), the Nuclear Regulatory Commission (NRC), the Department of Energy (DOE), and the Department of Transportation. In addition, the states and affected Indian Tribes play a prominent role in protecting the public against the hazards of radioactive waste.

Types Of Radioactive Waste

There are five general categories of radioactive waste: (1) spent nuclear fuel from nuclear reactors and high-level waste from the reprocessing of spent nuclear fuel, (2) transuranic waste mainly from defense programs, (3) uranium mill tailings from the mining and milling of uranium ore, (4) low-level waste, and (5) naturally occurring and accelerator-produced radioactive materials. Radioactive waste is categorized according to its origin and not necessarily according to its level of radioactivity. For example, some low-level waste has the same level of radioactivity as some high-level waste.

This booklet describes the different categories of waste, discusses disposal practices for each type. and describes the way they are regulated.

Spent Nuclear Fuel and High-level Radioactive Waste

Sources and Volume

In addition to being used to generate commercial electricity, nuclear reactors are used in government-sponsored research and development programs, universities and industry; in science and engineering experimental programs; at nuclear weapons production facilities; and by the U.S. Navy and military services. The operation of nuclear reactors results in spent reactor fuel. The reprocessing of that spent fuel produces high-level radioactive waste (HLW).

The fuel for most nuclear reactors consists of pellets of ceramic uranium dioxide that are sealed in hundreds of metal rods. These rods are bundled together to form what is known as a "fuel assembly." Depending upon the type and size of the reactor, a fuel assembly can weigh up to 1,500 pounds. As the nuclear reactor operates, uranium atoms fission (split apart) and release energy. When most of the usable uranium has fissioned, the "spent" fuel assembly is removed from the reactor.

Until a disposal or long-term storage facility is operational, most spent fuel is stored in water pools at the reactor site where it was produced. The water removes leftover heat generated by the spent fuel and serves as a radiation shield to protect workers at the site.

The operation of nuclear reactors over the last twenty years has substantially added to the amount of radioactive waste in this country. As shown in Figure 1, by the year 2020, the total amount of spent fuel is expected to increase significantly.

HLW is the liquid waste that results when spent fuel is reprocessed to recover unfissioned uranium and plutonium. During this process, the fuel is dissolved by strong chemicals, and this results in liquid HLW. Plans are to solidify these liquids into a form that is suitable for disposal. Solidification is still in the planning stages. While currently there are no commercial facilities in this country that reprocess spent fuel, spent fuel from defense program reactors has been routinely reprocessed for use in producing nuclear weapons or for reuse in new fuel.

Compared to the total inventory of HLW, the volume of commercial HLW from the reprocessing of commercial spent fuel is almost insignificant, less than one percent. Defense-related HLW comprises greater than ninety-nine percent of the volume of HLW. Figure 2 shows the historical and projected volume of defense-related HLW through the year 2020. The effect of the end of the "Cold War" on these projections is uncertain.

Figure 2

HLW is now stored in underground tanks or stainless steel silos on federal reservations in South Carolina, Idaho, and Washington and at the Nuclear Fuel Services Plant in West Valley, NY. These facilities have begun programs to solidify and structurally stabilize the waste in preparation for disposal at a national repository.

Regulation of Disposal

Some elements, such as plutonium, in HLW and spent fuel are highly radioactive and remain so for thousands of years. Therefore, the safe disposal of this waste is one of the most controversial environmental subjects facing the federal government and affected states.

The federal government (the EPA, the DOE, and the NRC) has overall responsibility for the safe disposal of HLW and spent fuel. The EPA is responsible for developing environmental standards that apply to both DOE-operated and NRC-licensed facilities. Currently, the NRC is responsible for licensing such facilities and ensuring their compliance with the EPA standards. DOE is responsible for developing the deep geologic repository which has been authorized by Congress for disposing of spent fuel and high level waste. Both the NRC and the Department of Transportation are responsible for regulating the transportation of these wastes to storage and disposal sites.

Site Selection for Storage and Disposal

In the early 1980's, the DOE formally adopted a national strategy to develop mined geologic repositories as disposal facilities for spent fuel and high-level radioactive waste. In 1983, the DOE identified nine potentially acceptable sites and, in 1984, selected three sites as candidates for further characterization. In 1987, Congress directed the DOE to pursue the investigation of only the Yucca Mountain, NV site in order to determine whether the site is suitable for development as a repository. The DOE has designed a comprehensive "site characterization" program to evaluate the suitability of the Yucca Mountain site. The objectives of this program are to: (1) determine the geologic, hydrologic, and geochemical conditions at Yucca Mountain; (2) provide information needed to design a package for the disposal of radioactive waste; (3) provide information for the design of the repository facility; and (4) evaluate whether Yucca Mountain can meet NRC and EPA protection and safety requirements. Figure 3 is an artist's rendition of the proposed Yucca Mountain repository.

The DOE is also developing plans for the siting and development of a potential Monitored Retrievable Storage (MRS) facility. The MRS facility could be used to receive and store spent fuel from commercial power reactors for subsequent shipment to a repository when such a facility becomes operational.

Setting Environmental Protection Standards

In 1985, the EPA published final regulations that established generally applicable environmental standards for the management and disposal of spent nuclear fuel, HLW, and transuranic (TRU) wastes. (TRU wastes are discussed in the next section.) The disposal portion of these standards was successfully challenged in the courts and returned to the Agency for revision. The court was primarily concerned that the regulations might not adequately protect ground water and individuals from radioactive contamination. Following the court's ruling in 1987, the EPA worked to re-promulgate the disposal portion of these standards.

In October 1992, two laws were enacted, the Waste Isolation Pilot Plant (WIPP) Land Withdrawal Act and the Energy Policy Act, that affected EPA's development of standards for the management and disposal of spent nuclear fuel, HLW and TRU wastes. As explained more fully in the next section on TRU waste, EPA's Administrator issued the revised disposal standards as mandated by the WIPP Land Withdrawal Act in December 1993. These standards apply to all HLW, spent fuel, and TRU waste disposal except for disposal at the Yucca Mountain site. The Energy Policy Act directs the EPA to issue environmental standards, which protect public health and safety and are specific to the Yucca Mountain site. The Act also requires that the National Academy of Sciences (NAS) conduct a study to provide findings and recommendations related to the form and content of environmental radiation protection standards for Yucca Mountain, Nevada. The EPA's standards for Yucca Mountain must be developed based upon the findings and recommendations of the NAS and must be issued within one year from the time ' the EPA receives the NAS recommendations. NRC, as the licensing authority for this site, must incorporate the EPA's environmental standards in their overall licensing regulations for HLW disposal (10 CFR 60).